1. Field of the Invention
The present invention relates to a communication apparatus which performs communication with a wireless communication medium such as RF-ID, that is, an IC card or an IC tag.
2. Description of the Related Art
In recent years, there has been proposed a mobile terminal such as a mobile phone which is provided with an RF-ID wireless tag or has a function of reading a non-contact IC card or IC tag. Further, as disclosed in Japanese Patent No. 4325621, a communication apparatus which employs an antenna device in which a coil axis of an antenna is perpendicular to a substrate has been widely used.
However, in the structure in which the coil axis is perpendicular to the substrate as in Japanese Patent No. 4325621, as will be described later, it is possible to read information when a non-contact IC card, for example, is disposed directly above the antenna device while being parallel to the substrate, but it is difficult to read information in other directions. That is, if the coil axis is perpendicular to a metal portion which is the substrate, magnetic lines flow one way approximately directly above a loop of the antenna. As a result, one-way magnetic lines are exerted to the non-contact IC card, and thus electric current is generated in the non-contact IC card. Thus, communication is performed between the mobile terminal and the non-contact IC card. However, in a direction other than the direction in which the non-contact IC card is disposed directly above the loop of the antenna, in particular, in a direction in which the non-contact IC card is disposed approximately directly across the loop of the antenna, magnetic lines which direct to the outside from the antenna side and magnetic lines which direct to the antenna side from the outside are generated. Thus, if the non-contact IC card is disposed approximately across the loop of the antenna while being approximately perpendicular to the metal portion, the magnetic lines in the opposite directions are generated to the non-contact IC card to then be canceled out. As a result, electric current cannot be generated in the non-contact IC card, and thus communication cannot be performed between the mobile terminal and the non-contact IC card.